Ablation behaviors of ultra-high temperature ceramic composites

In order to improve the oxidation resistance of carbon fibers reinforced carbon matrix composites (C/C and the thermal shock resistance of ultra-high temperature ceramics (UHTCs), large numbers of ZrB, based particles were introduced into CIC composites to fabricate the C/CC UHTC composites by powder infiltration (PI) and isothermal chemical vapor infiltration (ICV1). The effects of UHTC additive, heat flux and ablation time on the ablation behaviors of the C/C-UHTC composites were investigated through exposure to an oxyacetylene torch flame with ultra-high temperature. The ZrB, addition to the C/C pronouncedly improved the ablation resistance of the material under a 3920 kWm(2) heat flux and the C/C-ZrB2 showed a better ablation-resistive property compared to the C/C-4ZrB(2)-ISiC, C/C-2ZrB(2)-ISiC, C/C-2ZrB-ISiC-1HfC and C/C-2ZrB(2)-ISiC-ITaC. With decrease of the heat flux from 3200 to 2380 kW/m(2), the presence of a small amount of SiC in the C/C-ZrB, was found to have a positive role of improving the ablation resistance; the C/C-4ZrB(2)-ISiC exhibited a good ablation-resistive endurance under 2380 kW/m(2). The HfC addition was proved to effectively enhance the ablation property of the C/C-lZrB2-2SiC while the TaC addition severely deteriorated the property. (C) 2007 Elsevier B.V. All rights reserved.